The present invention relates generally to fluid ejection devices, and more particularly to a substrate for a fluid ejection device.
In some fluid ejection devices, such as printheads, a drop ejecting element is formed on a front side of a substrate and fluid is routed to an ejection chamber of the drop ejecting element through an opening or slot in the substrate. Often, the substrate is a silicon wafer and the slot is formed in the wafer by chemical etching. Existing methods of forming the slot through the substrate include etching into the substrate from both the front side and the backside thereof so as to form a front side opening and a backside opening in the substrate.
Unfortunately, since a portion of the slot is formed by etching into the substrate from the front side and a portion of the slot is formed by etching into the substrate from the backside, misalignment between the backside opening and the front side opening of the slot may occur. Such misalignment may result, for example, in undercutting of one or more layers formed on the front side of the substrate.
Accordingly, it is desired to accommodate misalignment between the backside opening and the front side opening of the slot through the substrate.
One aspect of the present invention provides a substrate for a fluid ejection device. The substrate includes a first side, a second side opposite the first side, spaced etch stops extending into the substrate from the first side, and a fluidic channel communicating with the first side and the second side, wherein a first portion of the fluidic channel extends from the first side toward the second side between the spaced etch stops and a second portion of the fluidic channel extends from the second side toward the first side to the spaced etch stops.